1. Field of the Invention
The present invention relates generally to an automatic transmission for transmitting torque from a prime mover to a drive train of a vehicle with a plurality of speed ratios.
2. Description of the Related Art
Automatic transmissions with an increased number of gear ratios have been proposed. In a vehicle with such an automatic transmission, a frequent up-shift or down-shift is performed to provide improved fuel efficiency and drivability. On the other hand, there is also a need for a lighter and more compact automatic transmission design by which auto manufactures can optimize the drive train layout that makes it possible to lower manufacturing cost and achieve improved fuel efficiency.
However, automatic transmissions with an increased number of gear ratios, for example, 6 or more speeds, tend to have a more complex design with an increased number of components that lead to an increase in volume and weight of the transmission which unfavorably affects manufacturing cost and fuel efficiency of the vehicle. Furthermore, problems of packaging components within a transmission which hinder assembly of the transmission into a vehicle have arisen.